Process for polymerizing vinyl chloride

ABSTRACT

An improved method for the polymerization of unsaturated compounds such as vinyl chloride or other ethylenically unsaturated monomers which involves using as an initiator in such process the chemical compound di-cetyl peroxydicarbonate having the structural formula   .

United States Patent [191 [111 3,903,065

Norback *Sept. 2, 1975 PROCESS FOR POLYMERIZING VINYL CHLORIDE [56] References Cited [75] Inventor: Hakan Norback, Danderyd, Sweden UNITED STATES PATENTS 73 Assigneez KemaNord AB, Stockholm, Sweden 3,022,281 2/1962 Srnith 260/928 W 3,637,633 l/l972 Dixon ct al. 260/928 W Notice: The portion of the term of this 3,720,700 3/1973 Norback 260/928 R patent subsequent to Mar. 13, 1990, has been disclaimed.

Filed: Feb. 22, 1973 Appl. No.: 334,560

Related US. Application Data Division of Scr. No. 876,802, Nov. 14, 1969, Pat. No. 3,720,700.

Foreign Application Priority Data Nov. 14. I968 Sweden 15458/68 Int. Cl. C08f 3/30 Field of Search 260/928 R Primary Examiner-Joseph L. Schofer Assistant ExaminerHerbert J. Lilling Attorney, Agent, or FirmFred Philpitt l 5 ABSTRACT 2 Claims, 1 Drawing Figure .09 Mo! Ce'ryl Peroxydicurbonote Per lOO kg Vinyl C loride 3.6 M ol Diluuroyl PeroxidePer lOOOkg.

Vinyl Chloride lOO so s l C .2 I 6C .3 as E B 49L I n 20 4 a q) Q Z 4 6 8 IO [2 l4 React ion Ti me (Hours) Degree Of Polymerisofion PATENTEU sEP 2 '97s .09 Mol Cefyi Peroxydicurbonofe Per lOO kg- Vinyl Chloride 3.6 Mol Dilouroyl Peroxide Per IOOOkg.

Vinyl Chloride loo 8 L so R'eocfion Ti me (Hours) PROCESS FOR POLYMERIZING VINYL CHLORIDE RELATED CASE This application is a division of my copending application Seri No. 876,802 now US. Pat. No.3,72(),700.

BACKGROUND It is known that compounds such as di-isopropyl-, din-butyl-, di-cyclohexyland di-tertiary-butyl cyclohexyl peroxydicarbonate are efficient initiators for the polymerization of unsaturated compounds such as ethylene, methyl methacrylate, vinyl chloride, vinylidene chloride, vinyl acetate, acrylamide, allyl chloroformate, and styrene. See for instance Dunn et al US. Pat. No. 2,843,576 and Marous et al Reissue US. Pat. No. 25,763.

However, these known initiators have several disadvantages. First of all, their stability to decomposition is poor. Concentrated di-isopropylperoxydicarbonate decomposes explosively at room temperature and other known peroxydicarbonates have, in a varying degree, poor storage stability. As a result considerable disadvantages and risks are involved in handling this type of initiator.

THE PRESENT INVENTION The present invention pertains to a process for polymerizing vinyl compounds (such as vinyl chloride) which comprises conducting the polymerization at 40 80C (or 45 65C) in the presence of 0.01 0.5 percent by weight (or 0.01 0.1 percent by weight) based on monomer, of di-cetyl peroxydicarbonate as initiator.

According to my invention it has been quite surprising to find that di-cetylperoxydicarbonate has superior storage stability as compared with known peroxydicarbonate initiators. My new compound can be stored at room temperatures for long periods of time without danger of self ignition and the active peroxide content decreases only insignificantly. Another advantage of di-cetylperoxydicarbonate is that it is in solid form and is free flowing, thus enabling charging of the initiator t the polymerization zone without waste and in an easy manner. A further advantage is that the decomposition product formed when the initiator reacts under the formation of free radicals is cetyl alcohol, which is not unwholesome or noxious for human beings. Consequently, my initiator is suitable for the manufacture of plastic materials that are later applied as wrapping material for food.

Di-cetylperoxydicarbonate has also unexpectedly proved to have the property of considerably reducing the number offish eyes compared to other initiators (such as di-tertiary-butyl cyclohexyl peroxydicarbonate.) This means that the resins manufactured with di-cetylperoxydicarbonate are not rendered unfit for use in such applications as tile insulation and foils.

Thus, distribution of the initiator from the manufacturer to the consumer usually has to be carried out by means of refrigerated transportation. Also, storage rooms at the point of use have to be adjusted to the thermosensibility of these compounds. Special precaution measures have to be taken to prevent fire in the storage rooms.

Another serious disadvantage of the hitherto used peroxydicarbonates (such as di-isopropyland ditertiary-butylcyclohexyl-peroxydicarbonate) is their tendency to form so called fish eyes. For instance when suspension polymerization of vinyl chloride is carried out with the aforesaid initiators is carried out, a fraction of the polyvinyl chloride granules that are obtained have a size of about millimicrons and have a relatively compact porous inner structure. When calendering such polyvinyl chloride granules with a plasticizer, the plasticizer cannot penetrate into these compact granules, so that they do not dissolve and will remain as small globules in the formed plastic product. These globules are called "fish eyes." These fish eyes" render the resin entirely unfit for certain purposes, such as for tile insulation and for thin foils.

Di-cetyl peroxydicarbonate can be employed for the polymerization of ethylenically unsaturated monomers, vinyl aromatic compounds e.g. styrene, pchlorostyrene, esters of aliphatic alpha-methylene mono carbonacids e.g. methylacrylate, n-butyl acrylate, ethylacrylate, acryl acid nitrile, vinyl esters e.g. vinyl acetate, vinyl halides e.g. vinyl chloride, vinyl ethers e.g. vinyl methylethers, vinylidene halides e.g. vinylidene chloride, alpha-ethylenically unsaturated hydrocarbon such as ethylene, propylene, as well as unsaturated polyesters. The type of polymerization preferably may be a suspension polymerization or a mass polymerization.

The advantages of di-cetyl peroxydicarbonate as a rapid and effective initiator become particularly apparent in the manufacture of polyvinyl chloride. The FlG URE compares the polymerization of vinyl chloride with (a) di-cetyl peroxydicarbonate as an initiator and (b) with the conventional dilauroyl peroxide as an initiator. When using di-cetyl peroxydicarbonate the polymerization time is reduced about one half in spite of the fact that only about one fourth as much di-cetyl peroxy dic arbonate was used.

I prefer to produce di-cetyl peroxydicarbonate by introducing liquid cetyl chloroformate under agitation to an alkaline aqueous solution of H 0 When the reaction has been completed the resulting product comprises white solid granules.

The following examples more specifically illustrate my concepts relative to di-cetyl peroxydicarbonate.

EXAMPLE 1 A 1000 ml three neck flask was charged with 500 ml distilled water in which 32 g of solid NaOI-I was dissolved. The temperature was regulated to 30C. by means of a thermostatically controlled bath whereupon 40 g of a 35 percent by weight aqueous solution of hydrogen peroxide was added. Under vigorous agitation g of cetyl-chloroformate was charged drop-wise over a period of about 20 minutes. After reaction for 1.5 hour the formed solid product was filtered off and after re-crystallization in carbon tetrachloride the product contained 98 percent by weight of peroxide calculated as di-cetyl peroxydicarbonate.

EXAMPLE 2 When storing various peroxydicarbonates at a temperature of 40C in a thermostatically controlled bath the following reduction of activity as a function of time was achieved.

(-peroxydicarhonate) reduction of activity at 40C lsopropylexplosive decomposition n-butylcomplete decomposition after 24 hours Z-ethylhexylcomplete decomposition after 36 hours cyclohexylcomplete decomposition after 24 hours tcrt.-butylcyclo- 56% reduction of activity after 20 days hexyldi-cetyl- 4% reduction of activity after 20 days EXAMPLE 3 PVC 200 parts by weight dioctylphthalate I parts by weight trihasic lead 4 parts by weight sulfate stearine 025 parts by weight soot (black) 1 part by weight Each mixture was calendered at a temperature of 150C for minutes whereupon the number of fish eyes per dm of the foil was determined.

Initiator (-pcroxydicarhonatc) fish eyes. number/dm" pcs di-isopropyl 70-l00 di-tert.hutylcyclnhcxyl 75-90 di-cctyl- 2-5 EXAMPLE 4 of initiator dicetylperoxidicarbonate. To this mixture was added 8 pounds of vinyl chloride and the suspension was agitated and heated to 50C. The reaction mixture was maintained at this temperature for 9 hours, after which time 88 percent of the vinyl chloride had been converted to polyvinyl chloride with a K-value of 72 when measured using 1 g polyvinyl chloride in 0.0. cyelohexanone. The number of fish eyes was 4 per square decimeter.

EXAMPLE 5 A stainless steel vessel was charged with 10 pounds of distilled water containing 6 g. of a suspension agent polyvinyl alcohol and 1.5 g of dicetylperoxidicarbonate. To the reaction vessel was then added 8 pounds of vinyl chloride. The reaction mixture was heated to 58C for 6 hours after which time the pressure had dropped to 3 kg/cm 91 percent of the vinyl chloride had been convered to polyvinyl chloride with a mean particle size of 0.1 mm and a bulk density of 550 g/l. The amount of fish eyes was very low, only 2 per square decimeter.

EXAMPLE 6 0.5 percent dicetyperoxidicarbonate was added and dissolved in methyl methacrylate. The solution was poured into a dish 5X5 cm and 1 cm thick. The mold itself was 0.4 cm thick and was maintained at a temperature of 30C for 2 days. A hard polymer with good transparency was prepared.

What we claim is:

l. A process for polymerizing vinyl chloride which comprises conducting the polymerization at 4080C in the presence of 0.0 l0.5 percent by weight, based on vinyl chloride, of di-cetyl peroxydicarbonate as initiator.

2. In the process of polymerizing vinyl chloride was an initiator, the improvement which comprises conducting the polymerization at 4565C in the presence of 0.0l-0.l percent by weight, based on monomer, of

di-cetyl peroxydicarbonate as the initiator.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,903,065

DATED September 2, 1975 INVENTOR(S) N H KAN It is certified that error appears ih the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 2, line 1, delete "was" and insert with Signed and Scaled this twenty-third D a y Of December 1 9 75 [SEAL] Attest: v

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Patents and Trademarks 

1. A PROCESS FOR POLYMERIZING VINYL CHLORIDE WHICH COMPRISES CONDUCTING THE POLYMERIZATION AT 40*-80*C IN THE PRESENCE OF 0.01-0.5 PERCENT BY WEIGHT BASED ON VINYL CHLORIDE, OF DI-CETYL PEROXYDICARBONATE AS INITIATOR.
 2. In the process of polymerizing vinyl chloride was an initiator, the improvement which comprises conducting the polymerization at 45*-65*C in the presence of 0.01-0.1 percent by weight, based on monomer, of di-cetyl peroxydicarbonate as the initiator. 